As discussed above, there's a distinct possibility that the lack of engagement relative to sub count harms you algorithmically when it comes to your series ranking in trending lists. (That's a maybe on Tapas. It's a definite on Webtoon's Top 30 lists, there's no question there.)
I'd absolutely avoid it for that reason alone. I get way more subs through ranking in the CANVAS Top 30 Sci-fi list on Webtoon whenever I post than I could have possibly got through sub-for-sub.
It also makes you look desperate. If your work is of good quality, it'll accumulate subs through normal promotion. If you need to bribe people to sub to you, I take that to mean there are some glaring issues with the comic which make people not want to sub unless there's something in it for them.
Just don't do it. It's a bad look, and can hurt your series algorithmically, long term.